1. Field of the Invention
This invention relates to a system for analyzing the colorimetric properties of a test sample and, more particularly, to improvements in systems of the type using a plurality of photodetectors providing signals at different wavelengths across a spectral band.
A need has developed within the prior art for automated spectrophotometric equipment designed to measure the colorimetric properties of a test sample at any predetermined wavelength or band of wavelengths. With the trend in the data processing industry towards smaller and smaller computers, this need for automated spectrophotometers has been met in part by integrating or incorporating a complete computer within the instrument system to provide completely self-contained automated systems. Such computers also act as controllers for not only operating the instrument and analyzing their results and providing some form of an output of the results, but also for controlling the operation of any sample handling equipment that might be used.
There has also been developed within the prior art improved means for detecting and analyzing a spectral band, such means being in a form of a self-scanning linear array of photodiodes. Such an array is advantageous because it can be operated at high speeds and thus can be readily operated taking advantage of the high speeds of modern computers. However, the arrays are also somewhat disadvantageous because of the fact that each of the photodiodes has to operate with sufficient light intensity to be above a dark current level but with an intensity below the saturation level of the photodiode in order to provide an accurate reading. Operation too near the dark current level or at saturation level will provide inaccurate or erroneous results.